Thread cutting mechanism



Jan. 19, 1937.

D. w, Kl'iAu THREAD CUTTING MECHANISM 2 Sheets-Sheet 1 Original Filed Feb. 24, 1933 IN\ IENTOR DczVzd WKZa zz Y h w ATTORNEY Jan. 19, 1937. D. w. KLAU I THREAD CUTTING MECHANISM Original Filed Feb. 24, 1933 2 Sheets-Sheet 2 INVENTOR DaVz'd Z'aa ATT NE Patented Jan. 19, 1937 QFiE THREAD CUTTING MECHANISM David W. Klan, New York, N. Y.

7 Claims.

This invention relates to a duplex sewing machine adap-ted for the making of two parallel lines of stitching simultaneously.

While this invention is particularly adapted for the hemming of the opposite parallel sides of a roller shade or the like, it will be obvious that it may be employed in other relations as well.

The present invention is in the nature of an improvement upon the machines disclosed and. claimed in my patents numbered 1,578,324; March 30th, 1926, and 1,608,944, November 30th, 1926; the present application being a division of application Serial No. 658,367, filed February 24th, 7

An object of the present invention is to provide an efficient thread cutting mechanism.

A further object is to provide improved cutting means for the thread which extends from one window shade or the like to another.

A further detailed object is to provide a practical and efficient thread cutter having no operative metallic shearing edges.

A further object is toprovide efficient operating mechanism for the blade or blades employed.

Other objects and aims of the invention, more or less specific than those referred to above, will be in part obvious and in part pointed out in the course of the following description of the elements, combinations, arrangements of parts and applications of principles constituting the invention; and the'scope of protection contemplated will be indicated in the appended claims.

In the accompanying drawings Which are to be taken as a part of this specification, and in which I have shown merely a preferred form of embodiment of the invention:-

Fig. 1 is a top plan View of a machine constructed in accordance with this invention.

Fig. 2 is a vertical sectional view of the upper portion of the machine, said section being taken approximately upon the plane of line II-II of Fig. 1 and looking in the direction of the arrows on said line, and

Fig. 3 is an enlarged vertical sectional View of the thread cutting mechanism and associated parts, the section being taken on the plane of line III-III of Fig. 1.

Referring to the drawings for describing in detail the exemplary structure which is illustrated therein, the reference character L indicates a main frame comprising a top or table portion having suitable legs as Il.

The top or table portion illustrated consists of two longitudinal members as '2 and 3, each of right angular cross section, ordinary commercial angle irons as illustrated being well adapted to the purpose. These longitudinal members are arranged with vertical flanges depending and spaced apart, the horizontal flanges projecting outwardly in opposite directions. End connecting members as 4 and 5 extend between and connect the longitudinal members 2 and 3.

Fixed to the inner surfaces of the vertical flanges of the longitudinal members 2 and 3 respectively are strips 8 and. 9, the upper longitudinal edge surfaces of which are spaced downwardly a slight distance below the upper surface of the horizontal flanges of said longitudinal members thereby to form angle recesses as It and H which collectively define a run-Way longitudinally of the machine adapted to slidably receive and support the two sewing machine elements as G and H, said sewing machine elements having bed plates as i2 and I3 respectively, the opposite longitudinal edge portions of which rest slidably in the angle recesses iii and H so that said machines may be slid easily toward and away from each other along the run-way.

Any suitable means may be provided by which to operate the two sewing machines or for moving them back and forth along their run-way so as to operate upon difierent widths of work, such for instance the means shown in the parent application.

The sewing machines G and H are reversely positioned, that is they are arranged so that they face toward each other.

The two sewing machines are thus adapted for running lines of stitching simultaneously in the same direction along a single piece of goods, as ior instance a piece of window shade cloth as 40, moving transversely across the table as indicated in Fig. 1.

The shade material 46 may be carried as a roll, as indicated at 4|, in brackets as 42 and 43 fixed to and movable with the sewing machines G and H respectively, the material being thus conveniently held so that it may unwind from the roll and pass directly beneath the stitching heads of the two sewing machines.

A particular purpose of the machine is that of stitching hems as 44t4 at the opposite longitudinal edge portions of window shades and the like. In this instance a number of separate pieces of window shade material are wound into a single roll M. After one piece has passed beneath the stitching heads of the sewing machines G and H the operator feeds along behind it the next piece from the roll M, and this operation is repeated as the stitching of the successive pieces proceeds.

Always a space of an inch or two occurs between the succeeding pieces of window shade material. The stitching threads continue across this space and must be severed so that the hemmed shades may be separately handled in the subsequent operations of completing them.

As a suitable means for quickly, simultaneously and surely cutting the stitching threads between successive window shades the machine includes the pair of thread cutters as d545 with which the present invention is more particularly concerned, said thread cutters being constructed and operated as follows:

. The two thread cutters A5 are identical. Each includes a body portion 45 having a pendant intermediate web part as M to which is attached a sharp cutting blade as 48, for instance a safety razor blade. A carrying stem 59 projects downwardly through a slot as it formed longitudinal- 1y through the horizontal flange of the table forming member 3 and into fixed sliding connection with a horizontal bar 55 mounted for parallel vertical movement in the space beneath the horizontal flange of said table member, the two thread cutters being mounted upon the same bar 5|, one adjacent one end of said bar and the other adjacent the opposite end of said bar, and the arrangement being such that a downward vertical movementof the bar will cause the cutting blades 48-l8 of the two thread cutters to move simultaneously downwardly through the slots 59, as illustrated particularly in Fig. 3.

Each thread cutter includes two separate presser feet as 52 and 53 carried by the body 46 one at the forward side of the cutting blade and the other at the rear side of the cutting blade. These presser feet are yieldably mounted, as by being carried upon supporting rods as 54-54 vertically slidable through the body 46, compression springs as 55 engaging about said rods and serving to urge the presser feet downwardly but affording opportunity for continued downward movement of the body when downward movement of the presser feet is obstructed by engagement against the top horizontal surface of the frame or table member 3.

Suitable connecting members, as indicated at li$5fi, extend between the sewing machines G and H respectively and the adjacent thread cutters operable to cause sliding movement of the thread cutters along the horizontal bar 5| corresponding with all longitudinal adjustments of the sewing machines along the table, and the disposition of the thread cutters is such that the cutting blades and the presser feet of the thread cutters stand always in alignment with the stitching threads as said threads issue from the sewing machines respectively and move along with the work, the position of the two thread cutters with respect to the two sewing machines and the work being substantially as illustrated in Fig. 1.

Suitable guide members til are comprised in the sewing machines adapted to be engaged by marginal portions of the passing work so as to guide the work with respect to the stitching needles and the thread cutters.

The connecting members 5556 are fixed to the sewing machines and engage slidably within vertically extending slots 6d of the thread cutters so that the thread cutters will move adjustably along the table with the sewing machines and yet be free for vertical, or thread cutting, movement at all times.

The horizontal bar 5| is floatingly supported to move readily up and down along a pair of guide rods 58-58 which extend loosely through apertures 59-59 formed in the opposite end portions of the bar, springs as fifi-6U being carried 1 by the guide rods positioned beneath the horizontal bar, and other, relatively lighter, springs 6 I6l being carried by the guide rods positioned above the horizontal bar, all of said springs pressing yieldingly against the bar and serving collectively to hold the bar in a normal relatively elevated position.

A foot treadle as 62 is provided and a suitable connecting frame as 63 extends between this treadle and the opposite end portions of the horizontal bar in such wise as to cause a horizontal downward movement of the bar bodily against the compression of the springs 6ll60 whenever the treadle 62 is depressed, the shape of the connecting frame 63 and the manner of attaching it to the horizontal bar being such as to apply equal downward pull against the opposite end portions of the horizontal bar, and to leave the intermediate portion of the horizontal bar free and unobstructed for longitudinal sliding movement of the thread cutters at the will of the operator.

The manner of operating the thread cutters is simple: The operator, noting that the work has moved along so that the end of a completely stitched piece of work has just passed the thread cutters and that only the loose threads extending from this finished piece to the next succeeding piece are stretched across the slots 59 beneath the cutting blades 43-48 and presser feet 52 and 53, suddenly presses down the foot treadle 62 so as to move the two thread cutters simultaneously downwardly. The presser feet normally stand in a horizontal plane slightly below the cutting edges of the cutting blades, as shown by full lines in Fig. 3, so that as the thread cutters move downwardly said presser feet first engage the threads and co-operate to clamp the threads at opposite sides of slots 50 against the top surface of the table member 3 thereby gripping and holding the threads stretched across the slots 53. The continued downward movement of the cutting blades causes the blades to pass through and sever the threads where the threads span the slots.

The severing of the threads at opposite margins of the work is thus accomplished instantly and with perfect reliability, and the operation is fully under the control of the operator.

Instantly the foot pressure is moved from treadle 62 the springs 683EIJ snap horizontal bar 5!, and consequently the two thread cutters, upward again to their normal position free of the passing work, the springs 6l-6l serving at this time to cushion the upward movement of the horizontal bar.

While the mechanism herein shown and described shows both of the sewing machines G and H, and associated parts, to be adjustably movable longitudinally of the table, it will be understood that if desired one of the machines and its associated parts may remain stationary, and even i to adjust one or both of the sewing machines to properly operate upon the particular width of goods to be hemmed, then proceed to feed the work from roll 4| across the table through the guide devices 51-51 and periodically snap down and release the treadle 62 to sever the stitching threads between the pieces of work as they are successively completed.

The guide devices 51-51 are important. Being carried by and movable with the respective sewing machines, they not only guide the work accurately with respect to the two. sewing needles and the two thread cutters, but they also always insure that the roll 4! of the work is properly centered longitudinally with respect to the two brackets 42 and 43 which support the roll of work.

The top surface of the table member 3, where the presser feet engage, as at 65, may be roughened if desired, and the under surfaces of the presser feet may be matingly roughened, or may be formed of a yielding material 'such as rubber, so as to more eiliciently frictionally grip and hold the threads against endwise sliding when the cutting blades are pressed against the threads.

As many changes could be made in this construction without departing from the scope of the invention as defined in the following claims, it is intended that all matter contained in the above description, or shown in the accompanying drawings, shall be interpreted as illustrative only and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is: w 1

1. A thread cutting device for sewing ma chines, comprising a pair of presser feet spaced apart and movable into and out of clamping engagement against spaced parts of the sewing machine structure and adapted thereby to clamp and hold against endwise movement a thread extending in otherwise unsupported relation between them, and a single thread cutting blade arranged in the space between said presser feet movable to engage and sever the unsupported portion of thread extending between said presser feet, together with means for operating said presser feet and cutting blade.

2. A thread cutting device for sewing machines, comprising a pair of presser feet spaced apart and movable intoand out of clamping engagement against spaced parts of the sewing machine structure and adapted thereby to clamp and hold against endwise movement a thread extending in otherwise unsupported relation between them, a single body member by which said presser feet are carried, yieldable connecting means between said presser feet and said body member permitting movement of the body member independently of the presser feet, a single thread cutting blade arranged in the space between said presser feet carried by and movable with said body member to engage and sever the unsupported portion of thread extending between said presser feet, and means for operating said body member.

3. In a sewing machine device comprising a table element along which stitched work may move from a sewing machine, said table element having a slot formed therethrough extending transversely of the path of movement of the work, and a thread cutting device also disposed in the path of movement of the work, said thread cutting device including a pair of yieldingly mounted presser feet one disposed at each side of said slot, means to move said presser feet into and out of clamping engagement against the parts of said table element at opposite sides of said slot respectively adapted thereby to clamp and hold against endwise movement a stitching thread extending in otherwise unsupported relation between them across said slot, and a single thread cutting blade arranged in the space between said presser feet movable into and out of said slot and hence into severing engagement with the unsupported portion of thread extending across said slot.

4. In a sewing machine device comprising a table element along which stitched work may move from a sewing machine, said table element having a slot formed therethrough extending transversely of the path of movement of the work, and a thread cutting device also disposed in the path of movement of the work, said thread cutting device including means operable to grip and hold a thread stretched across said slot and a single cutting blade to sever said stretched thread at a point removed from the sides of the slot.

5. In a sewing machine device comprising a table element along which stitched work may move from a sewing machine, said table element having a slot formed therethrough extending transversely of the path of movement of the work, and a thread cutting device also disposed in the path of movement of the work, said thread cutting device including means operable to hold a thread stretched across said slot and to sever said thread at a point spaced intermediate the opposite walls of said slot.

6. In a sewing machine device comprising a table element along which stitched work may move from a sewing machine, said table element having a slot formed therethrough extending transversely of the path of movement of the work, and a thread cutting device also disposed in the path of movement of the work, said thread cutting device including a single cutting blade movable into said slot to sever a thread at a point spaced intermediate the opposite walls of said slot, the thread being unsupported between the sides of the slot during the cutting operation.

'7. In a sewing machine device comprising a table element along which stitched work may move from a sewing machine, said table element having a slot formed therethrough extending transversely of the path of movement of the work, and a thread cutting device also disposed in the path of movement of the work, said thread cutting device including a single keen blade operable by movement toward said table to sever at a point intermediate the opposite walls of said slot a thread stretched across said slot, the thread being unsupported between the sides of the slot during the cutting operation.

DAVID W. KLAU. 

